SU1677600A1 - Method of magnetic-tape testing of weld seams - Google Patents

Abstract

This invention relates to magnetic flaw detection and can be used to detect internal defects in welds using a magnetic recording method. The purpose of the invention is to increase sensitivity due to detuning from interference caused by surface inhomogeneities of the weld, due to the fact that after co-magnetizing the product and the magnetic tape placed on the surface of the weld by a constant magnetic field, the magnetic tape is removed the seam surface of the second magnetic tape and affect the product of a half-wave alternating magnetic field with a polarity opposite to the polarity of the constant field, and with a frequency determined by the depth of Nost of the weld surface and magnetogram obtained by reading the joint on both bands. 4 il.

Description

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The invention relates to the field of magnetic flaw detection and can be used to detect internal defects in welds by the magnetic field method.

The purpose of the invention is to increase the sensitivity due to the detuning from interference caused by the surface inhomogeneities of the weld.

FIG. 1 shows a schematic diagram of the implementation of the method of magnetic inspection of welds: FIG. 2 shows a tape recorded on a magnetic tape when the weld is magnetized by a constant field; FIG. 3 shows a tape recorded on the second tape when the weld is magnetized by variables

field; 4 shows a magnetogram obtained by joint reading of two tapes.

The diagram of the method implementation shows the product 1 with a controlled weld seam 2 and an internal defect 3, a magnetic tape 4 and a magnetizing unit 5 placed on the weld seam 2. In FIG. 2-4, pulses 6 are marked from the edges of the tape, pulses 7 from the edges of the seam and pulses 8 from the defect.

The method of magnetographic control of welds is carried out as follows.

A magnetic tape 4 is applied to the controlled weld seam 2. The magnetic tape 4 is magnetized together with product 1 by a constant magnetic field N. As a result of the action of a constant magon VI VJ O O O

The magnetic field obtained by reading from this magnetic tape (figure 2) shows pulses 7 fields scattered from the edges of the seam, pulses 8 from defects 3, pulses 6 from the edges of the tape, as well as pulses caused by uneven surfaces of the weld (not shown in figure 2). Then tape A is removed from the weld surface, another tape is placed on the weld, and a half-wave alternating magnetic field is applied to the product. In this particular case, IH-I-IKU.

Since, due to the selected frequency, the alternating field does not penetrate deep into the weld metal, the field scattered from defects does not appear and the tape from this tape has the form shown in FIG.

Since the pulses on the magnetograms from both tapes (Figures 2 and 3), the pulses from the edges of the tape, the edges of the weld and from the surface irregularities, have the opposite direction, on the magnetogram obtained when read together with

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of both tapes, only pulses 8 are visible, due to an internal defect 3, i.e. interference compensation occurs.

Claims (1)

Claims The method of magnetographic control of welds, which imposes a tape on a weld, magnetizes it together with a product with a constant magnetic field, then applies an alternating magnetic field to the product, read a magnetogram and judge the quality of the weld the fact that, in order to increase sensitivity due to detuning from interference caused by surface irregularities of the weld, before applying an alternating magnetic field, the first magnetic tape is removed t, the surface of the article is applied a second magnetic tape, is applied to the product half-wave alternating magnetic field with a polarity opposite to the polarity of the DC field and a frequency determined by the depth of the irregularities of the weld surface and magnetogram obtained at joint read from both strands. f 1 Fi8.2  K1L 6 Fig 3